An electric wire connection structure using an electric connection box has been known as an electric wire (wiring member) connection structure making connection between an instrument panel side wire harness and a vehicle body side wire harness routed in a car (see PTL 1). Generally, in the electric wire connection structure using the electric connection box, connector fitting portions are provided at the electric connection box, and connectors at terminals of (branched) electric wires led out of main lines of the wire harnesses are connected to the connector fitting portions. That is, the electric wire of the instrument panel side wire harness and the electric wire of the vehicle body side wire harness are connected to each other through the connectors.